The invention relates generally to concrete articleforming devices, and relates specifically to an apparatus for forming concrete articles of uniform density.
Presently, devices for forming concrete into articles, such as lengths of concrete pipe, include a revolving packing head for packing concrete against the inner wall of a mold, a conveyor for feeding concrete into the area between the packing head and the mold inner wall as the article is being formed, and means for moving the packing head through the mold so as to form the article.
The density of concrete in each area of formation, as an article is being formed, is generally non-uniform in such devices. Such non-uniform density is a result of inefficient operator control of such devices. In operating such devices, the operator visually assesses the uniformity of density of concrete, and manually adjusts the rate of feeding concrete from the conveyor into the area of formation between the packing head and the mold as the article is being formed. Such operator-controlled procedures are highly inefficient and ineffective.
Non-uniform density of concrete in areas of formation as the article is being formed in such devices, resulting from inefficiency in such operator-controlled procedures, generates formation of stresses in the article, as the revolving motion of the packing head compacts such concrete of non-uniform density. In forming non-reinforced concrete articles in such devices, such stresses generate cracks which substantially weaken such articles, resulting in damage thereto, and leakage therefrom during use thereof. In forming reinforced concrete articles in such devices, such stresses generate bending and deflection of the reinforcing wire, which forms voids therein and substantially weaken such articles, resulting in damage thereto, and leakage therefrom during use thereof.